Metallic carrier compositions used in the treatment of various disorders have been heretofore suggested and/or utilized (see, for example, U.S. Pat. Nos. 4,849,209 and 4,106,488), and have included such compositions that are guided or controlled in a body in response to external application of a magnetic field (see, for example, U.S. Pat. Nos. 4,501,726, 4,652,257 and 4,690,130). Such compositions have not always proven practical and/or entirely effective. For example, such compositions may lack adequate capacity for carriage of the desired biologically active agent to the treatment site, have less than desirable magnetic susceptibility and/or be difficult to manufacture, store and/or use.
One such known composition, deliverable by way of intravascular injection, includes microspheres made up of a ferromagnetic component covered with a biocompatible polymer (albumin, gelatin, polysaccharides) which also contains a drug (Driscol C. F. et al. Prog. Am. Assoc. Cancer Res., 1980, p. 261).
It is possible to produce albumen microspheres up to 3.0 .mu.m in size containing a magnetic material (magnetite Fe.sub.3 O.sub.4) and the anti-tumoral antibiotic doxorubicin (Widder K. et al. J. Pharm. Sci., 68:79-82 1979). Such microspheres are produced through thermal and/or chemical denaturation of albumin in an emulsion (water in oil), with the input phase containing a magnetite suspension in a medicinal solution. Similar technique has been used to produce magnetically controlled, or guided, microcapsules covered with ethylcellulose containing the antibiotic mitomycin-C (Fujimoto S. et al., Cancer, 56: 2404-2410,1985).
Another method is to produce magnetically controlled liposomes 200 nm to 800 nm in size carrying preparations that can dissolve atherosclerotic formations. This method is based on the ability of phospholipids to create closed membrane structures in the presence of water (Gregoriadis G., Ryman B. E., Biochem. J., 124:58, 1971).
The above compositions require extremely high flux density magnetic fields for their control, and are somewhat difficult to produce consistently, sterilize, and store on an industrial scale without changing their designated properties.
To overcome these shortcomings, a method for producing magnetically controlled dispersion has been suggested (See European Patent Office Publication No. 0 451 299 A1, by Kholodov L. E., Volkonsky V. A., Kolesnik N. F. et al.), using ferrocarbon particles as a ferromagnetic material. The ferrocarbon particles are produced by heating iron powder made up of particles 100 .mu.m to 500 .mu.m in size at temperatures of 800.degree. C. to 1200.degree. C. in an oxygen containing atmosphere. The mixture is subsequently treated by carbon monoxide at 400.degree. C. to 700.degree. C. until carbon particles in an amount of about 10% to 90% by mass begin emerging on the surface. A biologically active substance is then adsorbed on the particles
This method of manufacturing ferrocarbon particles is rather complicated and requires a considerable amount of energy. Because the ferromagnetic component is oxidized due to the synthesis of ferrocarbon particles at a high temperature in an oxygen containing atmosphere, magnetic susceptibility of the dispersion obtained is decreased by about one-half on the average, as compared with metallic iron. The typical upper limit of adsorption of a biologically active substance on such particles is about 2.0% to 2.5% of the mass of a ferromagnetic particle.
The magnetically controlled particle produced by the above method has a spheroidal ferromagnetic component with a thread-like carbon chain extending from it and is generally about 2.0 .mu.m in size. The structure is believed to predetermine the relatively low adsorption capacity of the composites and also leads to breaking of the fragile thread-like chains of carbon from the ferromagnetic component during storage and transportation.
Further development in this field could thus still be utilized.